Method for molding glass-filled thermoplastic resins

Abstract

Glass fiber reinforced thermoplastic resins comprising glass fiber, a thermoplastic resin and a copolymer of an ethylenically-unsaturated monomer and from about 1 to about 20 wt. % of copolymerizable functional monomer exhibit a marked improvement in impact properties when melt processed in screw-fed melt processing equipment such as a screw-fed injection molding machine using back-pressures in the range 0-100 psi.

We claim: 
     
       1. A method for producing improved glass-filled thermoplastic resin articles comprising the steps of: providing a dry blend composition comprising a rigid thermoplastic monovinylidene resin, a glass reinforcing fiber and a copolymer of at least monovinylidene monomer selected from the group consisting of monovinyl aromatic compounds and acrylic compounds and from 1 to 20 wt.% of at least one ethylenically unsaturated monomer containing at least one functional radical selected from the group consisting of carbonyl radicals and epoxy radicals; and   melt-processing said composition in screw-fed means for resin processing at a back pressure of from 0 to 100 psi.   
     
     
       2. The method of claim 1 wherein said ethylenically-unsaturated monomer is selected from the group consisting of maleic anhydride, glycidyl methacrylate and N-alkoxymethyl acrylamide. 
     
     
       3. The method of claim 1 wherein said screw-fed means is a screw-fed injection molding machine. 
     
     
       4. The method of claim 1 wherein said monovinylidene resin is selected from the group consisting of styrenic resins and acrylic resins. 
     
     
       5. The method of claim 1 wherein the monovinylidene resin is a styrenic resin selected from the group consisting of polystyrene, styrene-acrylonitrile copolymers, styrene-alpha methylstyrene-acrylonitrile copolymers, styrene-methyl methacrylate copolymers, styrene-maleic anhydride copolymers, and high impact polystyrene. 
     
     
       6. The method of claim 1 wherein said monovinylidene resin is polymethyl methacrylate. 
     
     
       7. The method of claim 1 further comprising a non-styrenic thermoplastic resin. 
     
     
       8. The method of claim 1 further comprising polyphenylene ether.